Field of the Disclosure
The following relates generally to wireless communication, and more particularly to setting an inactivity timeout using distributed coordination function information.
Description of Related Art
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). A wireless network, for example a wireless local area network (WLAN), such as a Wi-Fi network (IEEE 802.11), may include an access point (AP) that may communicate with one or more stations (STAs) or mobile devices. The AP may be coupled to a network, such as the Internet, and enable a mobile device to communicate via the network (and/or communicate with other devices coupled to the access point).
WLAN systems may use channel sense multiple access (CSMA), in which devices or STAs sense channel conditions prior to accessing the channel. In WLAN systems, APs may be communicating with several or many other STAs concurrently, and therefore data transfers may be interrupted by periods where the AP is serving other STAs. A baseline power-saving algorithm may keep the STA awake for a fixed period of time after the last received/transmitted frame. However, a long fixed period will sacrifice power savings for performance, while a short fixed period will save power but sacrifice performance.
One approach is to use a packet arrival rate to adjust the period of time that the device remains in the awake mode after the last received/transmitted frame. The period of time may be referred to as inactivity time interval or inactivity timeout (ITO). The packet arrival rate, determined when the device is in the awake mode, may be used to guide the determination of the ITO. However, this approach suffers from a drawback that the packet arrival rate determination may be in error, for example, due to channel congestion.
A procedure known as the distributed coordination function (DCF) may allow multiple stations (STAs) to compete for access to the same channel while avoiding traffic collisions. The DCF may use CSMA to determine the availability of the medium to be accessed by STAs in a basic service set (BSS). Before any STA may transmit, the STA may wait one inter-frame spacing (IFS) plus a random backoff interval. If the medium is determine to be idle (i.e., available) during the backoff interval (timed with a backoff timer), the STA may access the medium and start transmission. If the medium is determined to be busy, the STA may wait for the medium to become idle, during which the STA may suspend or pause the backoff timer. The backoff interval may be generated as a random number within a range known as a contention window (CW). For each failed transmission attempt, the CW for the STA may be incremented to a next longer CW step until a maximum CW value is reached. When a transmission attempt is successful, the CW may be reset to a default value (e.g., a minimum CW value) for the next transmission.